The Oriental provinces of the Empire, pre serving Greek engineering traditions, were more scientific, as shown by frequent use of siphons. The Byzantine emperors continued the Roman traditions, as shown by the aqueducts of Valens and Justinian at Constantinople, in connection with which are the wonderful cistern-reservoirs in the city with their forests of columns. Adana, Alopsuestia, and many other Eastern cities were provided by Justinian with aqueducts. The Gothic kings attempted the same, as in the ex tremely bold viaduct at Spoleto, loftier than any Roman work; their work in Spain was continued by the Moors, as at Elvas. The Mohammedans throughout the East continued the construction of aqueducts; but the Middle Ages in Europe were comparatively inactive in this branch of engineering. The Gothic aqueduct at Solmona and that at C'outances are perhaps the finest in Europe of this age. The Renaissance renewed the art, beginning with the Roman popes of the Sixteenth Century. France soon followed suit, as in the aqueduct of Arceuil at Paris built for Marie de Medici in 1613, and that of Main tenon under Louis XIV. In 1753 Charles III. built the great aqueduct of Caserta, about 30 miles 1011g. The aqueduct of Marseilles, begun in 1847 and over 40 miles long, with 75 tunnels and several viaducts, is the only work of modern engineering construction comparable artistically to the Koman; it could have been built for a fraction of the cost ($1,200,000) by using si phons.
Among the European aqueducts constructed during the latter part of the Nineteenth Century may be mentioned, first, that conveying water from Loch latrine to Glasgow, built in 1855-60 and duplicated quite recently. The new water supply conduits of Manchester and Liverpool, built in 1881-92 and 1885-94, respectively, are partly masonry structures and partly pipe lines. The Liverpool supply is brought from Lake Vyrnwy, a distance of OS allies., partly in tun nel. Tin' Manchester supply comes from Lake Thirlmere, a distance of nearly 96 miles, through 36 miles of concrete conduit and 14',..; miles of tunnel, making 501/2 miles of masonry aqueduct, and through 45 miles of iron pipe. The largest tunnel is 81(:: miles in length, and the longest in verted siphon, of iron pipe, is about the same length. Another inverted siphon is under a head of 480 feet. The masonry aqueduct is 7 feet in diameter. In the United States notable aqueducts were completed by New York in 1842 and a second in 1890 (old and new Croton) ; Boston in 1848 and a second in 1878; Brooklyn in 1859; Baltimore in 1802 and a second in 1830; ‘Washington in 1863, with a second one begun in 1883, abandoned before fully completed and near ing completion in 1901 ; St. Louis, Mo., about 1893; the Metropolitan NA ater Board (Boston and surrounding towns) in 1897: Jersey City, in progress in 1901, but on this work masonry aqueducts and tunnels are used only where steel pipe lines are not available. Cast-iron, steel, or wood pipe is used in place of masonry aqueducts for nearly all American water-works, especially in recent years, and with the introduction of riveted steel pipes, the likelihood of using masonry is still further decreased. The one exception to this is in the ease of tunnels, and particularly the intake tunnels through which Chicago and other cities on the Great Lakes draw their supply. These intakes, however, hardly come in the same category as the aqueducts de scribed lucre.
The 014 Croton Aqueduct, supplying New York City, has a total length of 38.1 miles and a total fall of 43.7 feet, the ordinary grade being 1.1088 feet per mile. It is of brick-lined masonry, the bottom being an inverted arch of 6.75 feet chord, 0.75 feet versed sine: sides. 4 feet high, battered to 7.42 feet apart at top; covered with semi-circular arch, giving total interior height of 8.64 feet and cross-sectional area of 53.34 square feet. The Harlem River is crossed on a granite masonry arched bridge, 100 feet high in the clear, and about 1400 feet long, the water being conveyed in two 36-inch east-iron and one wrought-iron pipe, the latter added in 1860. The Manhattan Valley is crossed by inverted cast-iron pipe siphons, two miles long. the original two 36-inch pipes hieing supplemented by a 48-inch in 1853 and a (30-inch in 1861, the latter being reported as the largest iron pipe east up to that time. The aqueduct was
designed to carry 72.000,001) gallons a day. In 1865, the portion of aqueduct below Ninety second Street was replaced by two 72-inch cast iron pipes. for which three 48-inch pipes were substituted later on. Tuu 1870 another length of aqueduct within the city was replaced by six parallel lines of 48-inch east-iron pipe. mile long. This aqueduct was carried as near the surface as the grades would permit. The New Croton Aqueduct, like the old one, begins at Croton Lake, formed by a (lam on the Croton River, and extends to 135th Street, New York City. Its total length is 30.87 miles, or 33.25 miles if the pipe line extension to the Central Park reservoir is included. Of the masonry aqueduct, 29.63 miles is in tunnel, requiring shafts from 18 to 402 feet deep for its construction. In general the aqueduct is shaped like a horseshoe, 13.53 feet high and 13.6 feet wide, has a fall of 0.7 foot per mile and an original rated carrying capacity (sec below) of about 318,000,000 gallons a day. At the Jerome Park storage reservoir, in the north part of the city, and some 23 miles from the upper end, it is reduced to a rated capacity of 250,000,000 gal Ions a day and changed to a circular section, I21/4 feet in diameter, for over 6 miles. It crosses beneath the Harlem River, still as a masonry aqueduct. under 55 pounds pressure, when full, the aqueduct here being 10% feet in diameter, lined with east iron. The cost of the aqueduct varied from $89.98 to $123.25 per lineal foot in different sections and under vary ing. conditions. When the new aqueduct was de signed it was estimated that it would carry 318, 000,000 gallons a day, when flowing to a depth of 12.842 feet in the horseshoe sections. Gaugings after its completion fixed the carrying capacity at about 302,500,000 gallons. Careful studies made by Mr. John R. Freeman in 1899 (Report Upon .Wen: York's Water ,Supply, New York, 1900) led him to conclude that the aqueduct was then carrying 16 per cent. less for stated depths than shown by the earlier gaugings, part of the difference being due to deterioration of the inner surface.
The ll'achusett Aqueduct for Boston and vicin ity has a rated daily capacity of 300,000,000 gallons. It is 12 miles long, if the 3 miles of canal at its lower end are included, and leads from the site of a proposed masonry dam on the Nashua River, at Clinton, Mass., to the Sudbury reservoir, a part of the old Boston water-works now controlled by the Metropolitan Water Board. From this reservoir the water flows through the old Sudbury aqueduct, completed in Boston in 1878. The first two miles of the Wachnsett aqueduct is in tunnel, through rock so compact that about one-half of it required no lining. Where lining was needed brick was used. The floor of the tunnel is of brick, with a slope of 1 foot in 5000 feet. After the tunnel comes 7 miles of aqueduct, with a grade of I foot in 2500 feet, built in embankment or in excavation. Both tunnel and covered aqueduct were built in the general shape of a horseshoe, from to 13% feet wide and from 1014 to 11 feet 10 inches high, and were of concrete, with the lower por tion lined with one course of brick. Below the section just described there are 3 miles of open ehannel, or canal. The aqueduct is carried over the A SAa bet River on a handsome granite masonry bridge of seven 29%-feet spans.
The Cabin John Arch, which carries the first Washington aqueduct across a creek of the same name, was for many years the largest sin gle-span masonry bridge in the world, having a length of 220 feet, and rising to a height of 101 feet in the clear. The rise of the arch, from the spring line, is feet. ' The bridge is 20 feet wide and its total length is 420 feet. It was built of large granite blocks, with sandstone parapets and coping. It cost $237,000.
Consult: Frontinus, De dqutrductis (edited by Herschel, New York, 1900) ; Friedlander, Darstelinngen aus der Nittengeschichte Routs (Leipzig, I8SS-90) ; and Leger. Les traraux publie.s the Romains (Paris, 1875).